Problem: Highly modified urban soils are used to as substrates for urban vegetation, but we know little about their ecology. Structural soils are used in urban tree pits as substrates composed coarse materials for a rigid framework to support infrastructure while providing macro-pores for root growth. Typically, a small percentage of soil (<10%) is included to provide water and nutrient retention. Likewise, lightweight aggregates are often used as artificial media in greenroofs. We know very little of the soil ecology and biology of these artificial urban substrates. However, we know that soil biology is a critical component of soil quality and may be imperative the health and growth of plants in these challenging substrates.
Goals: The goals of this research are: (1) to describe the existing soil ecology in these substrates, (2) examine methods to establish soil organisms in these relatively inert substrates.
Methods: A survey of the soil ecology of Chicago's green roof soils is underway. Soil biochemical properties are being assessed in these substrates to gather baseline information. A microcosm study was conducted to assess the survival of Lumbricus terrestris and their effects on soil properties in structural soil substrates.
Personnel: This research is led by Dr. Bryant Scharenbroch and students working on these projects include: Doug Johnston (UIC) and Laureen Frevert (Aurora University).
Funding: The Morton Arboretum.
Scharenbroch, B.C. and D. Johnston. 2010. A microcosm study of the common night crawler earthworm (Lumbricus terrestris) and physical, chemical and biological properties of a designed urban soil. Urban Ecosystems 14:119-134.
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